Duodenal and colonic mucosal S100A8/A9 (calprotectin) expression is increased and correlates with the severity of select histologic lesions in dogs with chronic inflammatory enteropathy.

BACKGROUND: Calprotectin, a damage-associated molecular pattern protein of the S100/calgranulin family, is a potential marker of gastrointestinal inflammation in dogs and mainly originates from activated macrophages and granulocytes. Increased calprotectin concentrations are reported in feces and serum samples from dogs with chronic inflammatory enteropathy (CIE), but mucosal calprotectin expression has not been extensively investigated in canine CIE. Thus, we aimed to evaluate gastrointestinal mucosal concentrations of calprotectin in 62 dogs (44 dogs with CIE compared to 18 healthy Beagles) using a particle-enhanced turbidimetric immunoassay method. Additionally, we assessed the relationship of gastric, duodenal, jejunal, ileal, and colonic mucosal calprotectin levels with the clinical disease severity (canine clinical inflammatory bowel disease activity index, CIBDAI), histopathologic findings, clinical outcome, and serum albumin concentrations to further evaluate the potential of calprotectin as a biomarker for CIE. RESULTS: Mucosal calprotectin concentrations in dogs with CIE were significantly higher in the duodenum (median: 276.2 µg/g) and colon (median: 298.2 µg/g) compared to healthy controls (median: 94.3 µg/g, P = 0.0039; and median: 112.0 µg/g, P = 0.0061). Similar numerical differences in the ileum and cecum were not statistically significant, and mucosal calprotectin concentrations correlated significantly among the different gastrointestinal segments. Histologic lesion severity was linked to mucosal calprotectin concentrations for inflammatory and structural histology criteria in the duodenum and colon (all P < 0.05). Higher mucosal calprotectin levels in the duodenum and across all segments correlated with lower serum albumin concentrations (both P < 0.05); duodenal mucosal calprotectin concentrations were more than sixfold higher in hypoalbuminemic dogs (median: 1441 µg/g, n = 4) than normoalbuminemic dogs (median: 227 µg/g, n = 40). There was no significant association of mucosal calprotectin levels with CIBDAI scores or individual clinical outcomes. CONCLUSIONS: These results show that duodenal and colonic mucosal calprotectin concentrations are increased in dogs with CIE, providing further supporting evidence for the diagnostic potential of fecal calprotectin (presumably reflecting mucosal) concentrations and in dogs with CIE. Further longitudinal research is needed to assess changes in mucosal calprotectin concentrations with clinical response to treatment vs. mucosal disease remission and to determine the clinical utility of fecal calprotectin concentrations to diagnose and monitor dogs with CIE in clinical practice.

Duodenal Fluid Analysis as a Rewarding Approach to Detect Low-Abundance Mutations in Biliopancreatic Cancers.

Diagnosis of biliopancreatic cancers by the available serum tumor markers, imaging, and histopathological tissue specimen examination remains a challenge. Circulating cell-free DNA derived from matched pairs of secretin-stimulated duodenal fluid (DF) and plasma from 10 patients with biliopancreatic diseases and 8 control subjects was analyzed using AmpliSeq™ HD technology for Ion Torrent Next-Generation Sequencing to evaluate the potential of liquid biopsy with DF in biliopancreatic cancers. The median cfDNA concentration was greater in DF-derived than in plasma-derived samples. A total of 13 variants were detected: 11 vs. 1 were exclusive for DF relative to the plasma source, and 1 was shared between the two body fluids. According to the four-tier systems, 10 clinical tier-I-II (76.9%), 1 tier-III (7.7%), and 2 tier-IV (15.4%) variants were identified. Notably, the 11 tier-I-III variants were exclusively found in DF-derived cfDNA from five patients with biliopancreatic cancers, and were detected in seven genes (KRAS, TP53, BRAF, CDKN2A, RNF43, GNAS, and PIK3CA); 82% of the tier-I-III variants had a low abundance, with a VAF < 6%. The mutational profiling of DF seems to be a reliable and promising tool for identifying cancer-associated alterations in malignant cancers of the biliopancreatic tract.

Non-biopsy Strategy for the Diagnosis of Celiac Disease in Adults: A Narrative Review.

Celiac disease (CeD) diagnosis is a complicated process, requiring a multi-step procedure and a high level of clinical knowledge. Some scientific societies, mainly from Europe and North America, have proposed appropriate guidelines for the diagnosis and management of CeD. Since duodenal biopsy is particularly challenging for children, guidelines of the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition, presented in 2012 and updated in 2020, have made it possible to avoid the biopsy in symptomatic pediatric patients with high levels of IgA anti-transglutaminase. Several parallel, similar studies in adults support the non-biopsy strategy. However, several pros and cons exist in applying such a strategy. The present narrative review reports the current evidence and the implication of omitting biopsy in the diagnosis of CeD in adults.

2-ethylhexyl diphenyl phosphate exposure induces duodenal inflammatory injury through oxidative stress in chickens.

2-ethylhexyl diphenyl phosphate (EHDPHP) is a widely used organophosphorus flame retardant and plasticizer, which is commonly found in the environment. EHDPHP not only potentially harms the environment but also causes different degrees of damage to the organism. In this study, the duodenum of chicks was selected as the potential toxic target organ to explore the mechanism of duodenal injury induced by EHDPHP exposure. Ninety one-day-old healthy male chicks were selected and randomly divided into C1(control group), C2(solvent control group), L(800 mg/kg), M(1600 mg/kg), H(3200 mg/kg) according to different doses of EHDPHP after one week of environmental adaptation. The chicks were given continuous gavage for 14 d, 28 d, and 42 d. It was found that constant exposure to EHDPHP caused an increase in duodenal MDA content, a decrease in P-gp, SOD, GSH-Px activities, and a decrease in duodenal mucosal immune factor (sIgA, GSH-Px). The expression of sIgM and mucosal link proteins (CLDN, OCLN, ZO-1, JAM) decreased, and the expression of the inflammatory protein (NF-κB, COX2) in duodenal tissues was up-regulated. The results showed that continuous exposure to EHDPHP could cause duodenal oxidative stress, inflammation, and mucosal barrier damage in chicks, which provided a basis for studying the mechanism of toxic damage caused by EHDPHP in poultry.

Accessibility of Percutaneous Biopsy in Retrocolic-Placed Pancreatic Grafts With a Duodeno-Duodenostomy.

Duodeno-duodenostomy (DD) has been proposed as a more physiological alternative to conventional duodeno-jejunostomy (DJ) for pancreas transplantation. Accessibility of percutaneous biopsies in these grafts has not yet been assessed. We conducted a retrospective study including all pancreatic percutaneous graft biopsies requested between November 2009 and July 2021. Whenever possible, biopsies were performed under ultrasound (US) guidance or computed tomography (CT) guidance when the US approach failed. Patients were classified into two groups according to surgical technique (DJ and DD). Accessibility, success for histological diagnosis and complications were compared. Biopsy was performed in 93/136 (68.4%) patients in the DJ group and 116/132 (87.9%) of the DD group (p = 0.0001). The graft was not accessible for biopsy mainly due to intestinal loop interposition (n = 29 DJ, n = 10 DD). Adequate sample for histological diagnosis was obtained in 86/93 (92.5%) of the DJ group and 102/116 (87.9%) of the DD group (p = 0.2777). One minor complication was noted in the DD group. The retrocolic position of the DD pancreatic graft does not limit access to percutaneous biopsy. This is a safe technique with a high histological diagnostic success rate.

IgG4-related disease presenting with gastric outlet obstruction.

A woman in her 20s presented with 6 weeks of fever, persistent vomiting and 28% loss of body weight. Symptoms were refractory to treatment with antiemetics and broad spectrum antibiotics.Further investigation via oesophageogastroduedenoscopy revealed a large gastric ulcer and pyloric stricture, causing gastric outlet obstruction (GOO). Biopsies of the stomach and duodenum showed plasma cell infiltration with a large proportion being IgG4 positive.Treatment with methylprednisolone, and later prednisolone, quickly improved inflammatory markers and symptoms. Balloon dilatation of the pyloric stricture also improved vomiting, allowing eventual re-establishment of oral nutrition. The patient made a full recovery with maintenance treatment on mycophenolate mofetil.IgG4-related disease (IgG4-RD) is a multisystem disorder with unpredictable presentation. The case highlights diagnostic challenges in IgG4-RD and identifies it as a rare differential in upper gastrointestinal symptoms. To our knowledge this is the first published case of IgG4-RD in the duodenum causing GOO.

A human autoimmune organoid model reveals IL-7 function in coeliac disease.

In vitro models of autoimmunity are constrained by an inability to culture affected epithelium alongside the complex tissue-resident immune microenvironment. Coeliac disease (CeD) is an autoimmune disease in which dietary gluten-derived peptides bind to the major histocompatibility complex (MHC) class II human leukocyte antigen molecules (HLA)-DQ2 or HLA-DQ8 to initiate immune-mediated duodenal mucosal injury1-4. Here, we generated air-liquid interface (ALI) duodenal organoids from intact fragments of endoscopic biopsies that preserve epithelium alongside native mesenchyme and tissue-resident immune cells as a unit without requiring reconstitution. The immune diversity of ALI organoids spanned T cells, B and plasma cells, natural killer (NK) cells and myeloid cells, with extensive T-cell and B-cell receptor repertoires. HLA-DQ2.5-restricted gluten peptides selectively instigated epithelial destruction in HLA-DQ2.5-expressing organoids derived from CeD patients, and this was antagonized by blocking MHC-II or NKG2C/D. Gluten epitopes stimulated a CeD organoid immune network response in lymphoid and myeloid subsets alongside anti-transglutaminase 2 (TG2) autoantibody production. Functional studies in CeD organoids revealed that interleukin-7 (IL-7) is a gluten-inducible pathogenic modulator that regulates CD8+ T-cell NKG2C/D expression and is necessary and sufficient for epithelial destruction. Furthermore, endogenous IL-7 was markedly upregulated in patient biopsies from active CeD compared with remission disease from gluten-free diets, predominantly in lamina propria mesenchyme. By preserving the epithelium alongside diverse immune populations, this human in vitro CeD model recapitulates gluten-dependent pathology, enables mechanistic investigation and establishes a proof of principle for the organoid modelling of autoimmunity.

Diagnosing sucrase-isomaltase deficiency: a comparison of a 13C-sucrose breath test and a duodenal enzyme assay.

BACKGROUND: Reduced activity of the sucrase-isomaltase (SI) enzyme can cause gastrointestinal symptoms. Biochemical measurement of SI activity in small intestinal biopsies is presently considered the gold standard for the diagnosis of SI deficiency, but this invasive test is not suitable as a routine diagnostic tool. AIM: To evaluate a 13C-sucrose-breath test (13CSBT) as a diagnostic tool for SI deficiency in an adult population. METHODS: 13CSBT results were compared to sucrase activity measured in duodenal biopsies. RESULTS: Forty patients with gastrointestinal symptoms were included in the study, 4 of whom had celiac disease and the rest (n = 36) had normal histological findings. Nine patients (22.5%) had low sucrase activity measured using duodenal biopsies. No correlation was observed between enzymatic sucrase activity and the 13CSBT results. The 13CSBT-curves for the celiac patients versus patients with normal duodenal histology demonstrated that the patients with celiac disease were within the lower range of the distribution. CONCLUSION: We observed a mismatch between the 13CSBT results and the biochemically measured sucrase activity, suggesting that SI activity is not uniformly distributed throughout the small intestines. This methodological discrepancy should be acknowledged when diagnosing SI deficiency.

Redefining Histological Cell Counts Using a Standardized Method: The Leuven Intestinal Counting Protocol.

INTRODUCTION: The diagnosis of eosinophilic gastrointestinal diseases is largely based on mucosal eosinophil counts, but thresholds and normal ranges beyond the esophagus are debated, calling for much-needed methodological standardization. We aimed to develop a standardized workflow for duodenal cell quantification and estimate duodenal eosinophil and mast cell numbers in healthy controls. METHODS: Software-based histological cell quantification using free-sized or fixed-sized regions was developed and applied to digitized hematoxylin and eosin (H&E)-stained slides from 58 individuals (healthy controls [HCs] and patients with functional dyspepsia). Intraclass correlation coefficients (ICCs) compared inter-rater reliability between software-based and microscopic quantification. Reproducibility of the software-based method was validated in an independent cohort of 37 control and functional dyspepsia subjects. Eosinophil identification on H&E staining was compared to immunohistochemistry (IHC). Normal eosinophil (H&E) and mast cell (cKit) ranges were determined in 70 adult HCs. RESULTS: Eosinophil quantification on digitized slides demonstrated excellent (ICC = 0.909) and significantly improved reproducibility over microscopic evaluation (ICC = 0.796, P = 0.0014), validated in an independent cohort (ICC = 0.910). Duodenal eosinophils were more abundant around crypts than in villi ( P < 0.0001), while counts were similar on matched H&E- and IHC-stained slides ( P = 0.55). Mean ± SD (95th percentile) duodenal eosinophils and mast cells in HC were 228.8/mm 2 ± 94.7 (402.8/mm 2 ) and 419.5/mm 2 ± 132.2 (707.6/mm 2 ), respectively. DISCUSSION: We developed and validated a standardized approach to duodenal histological cell quantification, generalizable to various mucosal cell types. Implementation of software-based quantification identified 400 eosinophils/mm 2 and 700 mast cells/mm 2 as thresholds for abnormal duodenal infiltration.

Persistent dysbiosis of duodenal microbiota in patients with controlled pediatric Crohn's disease after resolution of inflammation.

Crohn's disease is an inflammatory condition of the intestine characterized by largely unknown etiology and a relapse remission cycle of disease control. While possible triggers have been identified, research is inconsistent on the precise cause of these relapses, especially in the under-researched pediatric population. We hypothesized that patients in remission would have persistent microbial and inflammatory changes in small intestinal tissue that might trigger relapse. To this end, we analyzed intestinal biopsy samples from six patients with pediatric Crohn's disease in remission and a control group of 16 pediatric patients with no evident pathogenic abnormality. We identified compositional microbiota differences, including decreases in the genera Streptococcus and Actinobacillus as well as increases in Oribacterium and Prevotella in patients with controlled Crohn's disease compared to controls. Further, a histologic analysis found that patients with controlled Crohn's disease had increased epithelial integrity, and decreased intraepithelial lymphocytes compared with controls. Additionally, we observed increased peripheral CD4+ T cells in patients with pediatric Crohn's disease. These results indicate that markers of intestinal inflammation are responsive to Crohn's disease treatment, however the interventions may not resolve the underlying dysbiosis. These findings suggest that persistent dysbiosis may increase vulnerability to relapse of pediatric Crohn's disease. This study used a nested cohort of patients from the Bangladesh Environmental Enteric Dysfunction (BEED) study (ClinicalTrials.gov ID: NCT02812615 Date of first registration: 24/06/2016).

Single cell transcriptomic analysis of the canine duodenum in chronic inflammatory enteropathy and health.

Chronic inflammatory enteropathy (CIE) is a common condition in dogs causing recurrent or persistent gastrointestinal clinical signs. Pathogenesis is thought to involve intestinal mucosal inflammatory infiltrates, but histopathological evaluation of intestinal biopsies from dogs with CIE fails to guide treatment, inform prognosis, or correlate with clinical remission. We employed single-cell RNA sequencing to catalog and compare the diversity of cells present in duodenal mucosal endoscopic biopsies from 3 healthy dogs and 4 dogs with CIE. Through characterization of 35,668 cells, we identified 31 transcriptomically distinct cell populations, including T cells, epithelial cells, and myeloid cells. Both healthy and CIE samples contributed to each cell population. T cells were broadly subdivided into GZMAhigh (putatively annotated as tissue resident) and IL7Rhigh (putatively annotated as non-resident) T cell categories, with evidence of a skewed proportion favoring an increase in the relative proportion of IL7Rhigh T cells in CIE dogs. Among the myeloid cells, neutrophils from CIE samples exhibited inflammatory (SOD2 and IL1A) gene expression signatures. Numerous differentially expressed genes were identified in epithelial cells, with gene set enrichment analysis suggesting enterocytes from CIE dogs may be undergoing stress responses and have altered metabolic properties. Overall, this work reveals the previously unappreciated cellular heterogeneity in canine duodenal mucosa and provides new insights into molecular mechanisms which may contribute to intestinal dysfunction in CIE. The cell type gene signatures developed through this study may also be used to better understand the subtleties of canine intestinal physiology in health and disease.

The Usefulness of Intraepithelial Lymphocyte Immunophenotype Testing for the Diagnosis of Coeliac Disease in Clinical Practice.

BACKGROUND: The diagnosis of coeliac disease (CD) in adults is based on clinical, serological and histological criteria. The inappropriate performance of intestinal biopsies, non-specificity of mild histological lesions and initiation of a gluten-free diet (GFD) before biopsy may hamper the diagnosis. In these situations, determining the intraepithelial lymphogram of the duodenum by flow cytometry (IEL-FC) can be helpful. OBJECTIVES: To describe the clinical scenarios in which the IEL-FC is used and its impact on the diagnosis of CD. METHODS: All adult patients with suspected CD at three tertiary centres for whom the duodenal histology and IEL-FC were available were identified. Catassi and Fasano's diagnostic criteria and changes to a CD diagnosis after the IEL-FCs were collected. RESULTS: A total of 348 patients were included. The following indications for an IEL-FC formed part of the initial study for CD (38%): negative conventional work-up (32%), already on a GFD before duodenal biopsies (29%) and refractoriness to a GFD (2%). The IEL-FC facilitated a definitive diagnosis in 93% of patients with an uncertain diagnosis who had had a conventional work-up for CD or who were on a GFD before histology. CONCLUSIONS: The IEL-FC facilitates the confirmation or rejection of a diagnosis of CD in clinical scenarios in which a conventional work-up may be insufficient.

Transcriptomic analysis of intestine following administration of a transglutaminase 2 inhibitor to prevent gluten-induced intestinal damage in celiac disease.

Transglutaminase 2 (TG2) plays a pivotal role in the pathogenesis of celiac disease (CeD) by deamidating dietary gluten peptides, which facilitates antigenic presentation and a strong anti-gluten T cell response. Here, we elucidate the molecular mechanisms underlying the efficacy of the TG2 inhibitor ZED1227 by performing transcriptional analysis of duodenal biopsies from individuals with CeD on a long-term gluten-free diet before and after a 6-week gluten challenge combined with 100 mg per day ZED1227 or placebo. At the transcriptome level, orally administered ZED1227 effectively prevented gluten-induced intestinal damage and inflammation, providing molecular-level evidence that TG2 inhibition is an effective strategy for treating CeD. ZED1227 treatment preserved transcriptome signatures associated with mucosal morphology, inflammation, cell differentiation and nutrient absorption to the level of the gluten-free diet group. Nearly half of the gluten-induced gene expression changes in CeD were associated with the epithelial interferon-γ response. Moreover, data suggest that deamidated gluten-induced adaptive immunity is a sufficient step to set the stage for CeD pathogenesis. Our results, with the limited sample size, also suggest that individuals with CeD might benefit from an HLA-DQ2/HLA-DQ8 stratification based on gene doses to maximally eliminate the interferon-γ-induced mucosal damage triggered by gluten.

Insights into coeliac disease diagnosis: a 2021-2023 overview of diagnostic approach and delays in children in Slovenia.

INTRODUCTION: Over the past decade, the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) proposed the option of diagnosing coeliac disease (CD) in children without duodenal biopsy. The aim of our study was to assess the diagnostic approach in newly diagnosed children with CD in Slovenia. METHODS: In this prospective study, Slovenian paediatric gastroenterologists were invited to provide medical records of children under 19 years diagnosed with CD from March 2021 to October 2023. The analysis focused on tissue transglutaminase antibody (TGA) levels at diagnosis, diagnostic approach, adherence to ESPGHAN CD guidelines and diagnostic delays. RESULTS: Data from 160 newly diagnosed CD patients (61.9% female; median age 8 years; 16.9% asymptomatic) were available for the analysis. No-biopsy approach was used in 65% (N = 104) of children and the majority (N = 101) fulfilled all the criteria for the no-biopsy approach. Of 56 children diagnosed using duodenal biopsy, a further 10 (17.8%) would have also been eligible for the no-biopsy approach based on the very high levels of TGA. Median diagnostic delay from first symptoms to confirmation of diagnosis was 6 months (min 0 months, max 87 months). Use of the no-biopsy approach has risen significantly since 2016 (37.8% vs. 65.0%; p = 0.001) and diagnostic delays have shortened (6 vs. 7 months; p < 0.05). CONCLUSION: This prospective study highlights the frequent use of a no-biopsy approach for diagnosing CD in children in Slovenia, showing large adherence to ESPGHAN guidelines. Also, diagnostic delays have shortened over recent years, likely due to various awareness-raising projects on CD conducted during this period.

A shared group of bacterial taxa in the duodenal microbiota of undernourished Pakistani children with environmental enteric dysfunction.

Environmental enteric dysfunction (EED) is a subclinical syndrome of altered small intestinal function postulated to be an important contributor to childhood undernutrition. The role of small intestinal bacterial communities in the pathophysiology of EED is poorly defined due to a paucity of studies where there has been a direct collection of small intestinal samples from undernourished children. Sixty-three members of a Pakistani cohort identified as being acutely malnourished between 3 and 6 months of age and whose wasting (weight-for-length Z-score [WLZ]) failed to improve after a 2-month nutritional intervention underwent esophagogastroduodenoscopy (EGD). Paired duodenal luminal aspirates and duodenal mucosal biopsies were obtained from 43 children. Duodenal microbiota composition was characterized by sequencing bacterial 16S rRNA gene amplicons. Levels of bacterial taxa (amplicon sequence variants [ASVs]) were referenced to anthropometric indices, histopathologic severity in biopsies, expression of selected genes in the duodenal mucosa, and fecal levels of an immunoinflammatory biomarker (lipocalin-2). A "core" group of eight bacterial ASVs was present in the duodenal samples of 69% of participants. Streptococcus anginosus was the most prevalent, followed by Streptococcus sp., Gemella haemolysans, Streptococcus australis, Granulicatella elegans, Granulicatella adiacens, and Abiotrophia defectiva. At the time of EGD, none of the core taxa were significantly correlated with WLZ. Statistically significant correlations were documented between the abundances of Granulicatella elegans and Granulicatella adiacens and the expression of duodenal mucosal genes involved in immune responses (dual oxidase maturation factor 2, serum amyloid A, and granzyme H). These results suggest that a potential role for members of the oral microbiota in pathogenesis, notably Streptococcus, Gemella, and Granulicatella species, warrants further investigation.IMPORTANCEUndernutrition among women and children is a pressing global health problem. Environmental enteric dysfunction (EED) is a disease of the small intestine (SI) associated with impaired gut mucosal barrier function and reduced capacity for nutrient absorption. The cause of EED is ill-defined. One emerging hypothesis is that alterations in the SI microbiota contribute to EED. We performed a culture-independent analysis of the SI microbiota of a cohort of Pakistani children with undernutrition who had failed a standard nutritional intervention, underwent upper gastrointestinal tract endoscopy, and had histologic evidence of EED in their duodenal mucosal biopsies. The results revealed a shared group of bacterial taxa in their duodenums whose absolute abundances were correlated with levels of the expression of genes in the duodenal mucosa that are involved in inflammatory responses. A number of these bacterial taxa are more typically found in the oral microbiota, a finding that has potential physiologic and therapeutic implications.

Type 1 diabetes human enteroid studies reveal major changes in the intestinal epithelial compartment.

Lack of understanding of the pathophysiology of gastrointestinal (GI) complications in type 1 diabetes (T1D), including altered intestinal transcriptomes and protein expression represents a major gap in the management of these patients. Human enteroids have emerged as a physiologically relevant model of the intestinal epithelium but establishing enteroids from individuals with long-standing T1D has proven difficult. We successfully established duodenal enteroids using endoscopic biopsies from pediatric T1D patients and compared them with aged-matched enteroids from healthy subjects (HS) using bulk RNA sequencing (RNA-seq), and functional analyses of ion transport processes. RNA-seq analysis showed significant differences in genes and pathways associated with cell differentiation and proliferation, cell fate commitment, and brush border membrane. Further validation of these results showed higher expression of enteroendocrine cells, and the proliferating cell marker Ki-67, significantly lower expression of NHE3, lower epithelial barrier integrity, and higher fluid secretion in response to cAMP and elevated calcium in T1D enteroids. Enteroids established from pediatric T1D duodenum identify characteristics of an abnormal intestinal epithelium and are distinct from HS. Our data supports the use of pediatric enteroids as an ex-vivo model to advance studies of GI complications and drug discovery in T1D patients.

Selective activation of naïve B cells with unique epitope specificity shapes autoantibody formation in celiac disease.

Many antibody responses induced by infection, vaccination or autoimmunity show signs of convergence across individuals with epitope-dependent selection of particular variable region gene segments and complementarity determining region 3 properties. However, not much is known about the relationship between antigen-specific effector cells and antigen-specific precursors present in the naïve B-cell repertoire. Here, we sought to address this relationship in the context of celiac disease, where there is a stereotyped autoantibody response against the enzyme transglutaminase 2 (TG2). By generating TG2-specific monoclonal antibodies from both duodenal plasma cells and circulating naïve B cells, we demonstrate a discord between the naïve TG2-specific repertoire and the cells that are selected for autoantibody production. Hence, the naïve repertoire does not fully reflect the epitope preference and gene usage observed for memory B cells and plasma cells. Instead, distinct naïve B cells that target particular TG2 epitopes appear to be selectively activated at the expense of TG2-binding B cells targeting other epitopes.

Clinical manifestations, diagnosis and long-term prognosis of adult autoimmune enteropathy: Experience from Peking Union Medical College Hospital.

BACKGROUND: Autoimmune enteropathy (AIE) is a rare disease whose diagnosis and long-term prognosis remain challenging, especially for adult AIE patients. AIM: To improve overall understanding of this disease's diagnosis and prognosis. METHODS: We retrospectively analyzed the clinical, endoscopic and histopathological characteristics and prognoses of 16 adult AIE patients in our tertiary medical center between 2011 and 2023, whose diagnosis was based on the 2007 diagnostic criteria. RESULTS: Diarrhea in AIE patients was characterized by secretory diarrhea. The common endoscopic manifestations were edema, villous blunting and mucosal hyperemia in the duodenum and ileum. Villous blunting (100%), deep crypt lymphocytic infiltration (67%), apoptotic bodies (50%), and mild intraepithelial lymphocytosis (69%) were observed in the duodenal biopsies. Moreover, there were other remarkable abnormalities, including reduced or absent goblet cells (duodenum 94%, ileum 62%), reduced or absent Paneth cells (duodenum 94%, ileum 69%) and neutrophil infiltration (duodenum 100%, ileum 69%). Our patients also fulfilled the 2018 diagnostic criteria but did not match the 2022 diagnostic criteria due to undetectable anti-enterocyte antibodies. All patients received glucocorticoid therapy as the initial medication, of which 14/16 patients achieved a clinical response in 5 (IQR: 3-20) days. Immunosuppressants were administered to 9 patients with indications of steroid dependence (6/9), steroid refractory status (2/9), or intensified maintenance medication (1/9). During the median of 20.5 months of follow-up, 2 patients died from multiple organ failure, and 1 was diagnosed with non-Hodgkin's lymphoma. The cumulative relapse-free survival rates were 62.5%, 55.6% and 37.0% at 6 months, 12 months and 48 months, respectively. CONCLUSION: Certain histopathological findings, including a decrease or disappearance of goblet and Paneth cells in intestinal biopsies, might be potential diagnostic criteria for adult AIE. The long-term prognosis is still unsatisfactory despite corticosteroid and immunosuppressant medications, which highlights the need for early diagnosis and novel medications.

Pseudomelanosis of the duodenum and stomach.

Pseudomelanosis duodeni is characterized by endoscopic findings of black or black-brown speckled pigmentation in the duodenal mucosa, usually diagnosed via biopsy. This report presents a case of a 75-year-old male presented with left lower abdominal pain, change in bowel habits, and decreased appetite. Gastroduodenoscopy and biopsies of the duodenum and antrum lead to the diagnosis of pseudomelanosis duodeni.

Yield of Gluten Challenge in Patients on Self-Prescribed Gluten-Free Diets.

BACKGROUND: Patients on a gluten-free diet (GFD) whose celiac disease (CD) status is unknown may undergo gluten challenge (GC) to clarify their diagnosis. Though this is an established diagnostic practice, the proportion of patients undergoing GC who are diagnosed with CD is unknown. AIMS: We aimed to analyze which factors were predictive of having CD in a cohort of patients who underwent GC followed by upper endoscopy with duodenal biopsy. METHODS: We identified adult patients at a CD referral center who had been on a GFD and then underwent GC to determine a diagnosis of CD during the years spanning 2006 to 2020. We compared those patients found to have CD (defined as villus atrophy/Marsh 3) on duodenal biopsy with those who did not, using the chi square and Fischer exact tests. RESULTS: We identified 206 patients who underwent GC. Of these 206, 30 (14%) were diagnosed with CD based on post-GC duodenal biopsy. 176 of the 206 (85%) patients reported various gastrointestinal symptoms, including bloating (39%), though these were more common in those without CD (any GI symptoms: 89% vs 67%, p 0.004; bloating: 43% vs 20%, p 0.019). Serology values, when normalized, including pre- and post-challenge TTG IgA (37% vs 1.7%, p 0.001; 23% versus 2.3%, p 0.001), DGP IgG and IgA (57% vs 2.8%, p 0.001; 37% vs 6.2%, p 0.001) were higher in the group of patients with CD. CONCLUSION: Among patients undergoing GC for diagnostic purposes, only 14% had evidence of villus atrophy corresponding with CD on duodenal biopsy. The presence of any elevated pre-challenge serology was associated with CD. Bloating in combination with low serologies may help risk stratify patients as being less likely to have CD upon GC.